// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_KEYS_H_
#define V8_KEYS_H_

#include "src/objects.h"
#include "src/objects/hash-table.h"
#include "src/objects/js-objects.h"

namespace v8 {
namespace internal {

    class JSProxy;

    enum AddKeyConversion { DO_NOT_CONVERT,
        CONVERT_TO_ARRAY_INDEX };

    // This is a helper class for JSReceiver::GetKeys which collects and sorts keys.
    // GetKeys needs to sort keys per prototype level, first showing the integer
    // indices from elements then the strings from the properties. However, this
    // does not apply to proxies which are in full control of how the keys are
    // sorted.
    //
    // For performance reasons the KeyAccumulator internally separates integer keys
    // in |elements_| into sorted lists per prototype level. String keys are
    // collected in |string_properties_|, a single OrderedHashSet (similar for
    // Symbols in |symbol_properties_|. To separate the keys per level later when
    // assembling the final list, |levelLengths_| keeps track of the number of
    // String and Symbol keys per level.
    //
    // Only unique keys are kept by the KeyAccumulator, strings are stored in a
    // HashSet for inexpensive lookups. Integer keys are kept in sorted lists which
    // are more compact and allow for reasonably fast includes check.
    class KeyAccumulator final {
    public:
        KeyAccumulator(Isolate* isolate, KeyCollectionMode mode,
            PropertyFilter filter)
            : isolate_(isolate)
            , mode_(mode)
            , filter_(filter)
        {
        }
        ~KeyAccumulator() = default;

        static MaybeHandle<FixedArray> GetKeys(
            Handle<JSReceiver> object, KeyCollectionMode mode, PropertyFilter filter,
            GetKeysConversion keys_conversion = GetKeysConversion::kKeepNumbers,
            bool is_for_in = false, bool skip_indices = false);

        Handle<FixedArray> GetKeys(
            GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
        Maybe<bool> CollectKeys(Handle<JSReceiver> receiver,
            Handle<JSReceiver> object);
        Maybe<bool> CollectOwnElementIndices(Handle<JSReceiver> receiver,
            Handle<JSObject> object);
        Maybe<bool> CollectOwnPropertyNames(Handle<JSReceiver> receiver,
            Handle<JSObject> object);
        void CollectPrivateNames(Handle<JSReceiver> receiver,
            Handle<JSObject> object);
        Maybe<bool> CollectAccessCheckInterceptorKeys(
            Handle<AccessCheckInfo> access_check_info, Handle<JSReceiver> receiver,
            Handle<JSObject> object);

        // Might return directly the object's enum_cache, copy the result before using
        // as an elements backing store for a JSObject.
        // Does not throw for uninitialized exports in module namespace objects, so
        // this has to be checked separately.
        static Handle<FixedArray> GetOwnEnumPropertyKeys(Isolate* isolate,
            Handle<JSObject> object);

        void AddKey(Object key, AddKeyConversion convert = DO_NOT_CONVERT);
        void AddKey(Handle<Object> key, AddKeyConversion convert = DO_NOT_CONVERT);
        void AddKeys(Handle<FixedArray> array, AddKeyConversion convert);
        void AddKeys(Handle<JSObject> array_like, AddKeyConversion convert);

        // Jump to the next level, pushing the current |levelLength_| to
        // |levelLengths_| and adding a new list to |elements_|.
        Isolate* isolate() { return isolate_; }
        // Filter keys based on their property descriptors.
        PropertyFilter filter() { return filter_; }
        // The collection mode defines whether we collect the keys from the prototype
        // chain or only look at the receiver.
        KeyCollectionMode mode() { return mode_; }
        // In case of for-in loops we have to treat JSProxy keys differently and
        // deduplicate them. Additionally we convert JSProxy keys back to array
        // indices.
        void set_is_for_in(bool value) { is_for_in_ = value; }
        void set_skip_indices(bool value) { skip_indices_ = value; }
        // The last_non_empty_prototype is used to limit the prototypes for which
        // we have to keep track of non-enumerable keys that can shadow keys
        // repeated on the prototype chain.
        void set_last_non_empty_prototype(Handle<JSReceiver> object)
        {
            last_non_empty_prototype_ = object;
        }
        // Shadowing keys are used to filter keys. This happens when non-enumerable
        // keys appear again on the prototype chain.
        void AddShadowingKey(Object key);
        void AddShadowingKey(Handle<Object> key);

    private:
        Maybe<bool> CollectOwnKeys(Handle<JSReceiver> receiver,
            Handle<JSObject> object);
        Maybe<bool> CollectOwnJSProxyKeys(Handle<JSReceiver> receiver,
            Handle<JSProxy> proxy);
        Maybe<bool> CollectOwnJSProxyTargetKeys(Handle<JSProxy> proxy,
            Handle<JSReceiver> target);
        Maybe<bool> AddKeysFromJSProxy(Handle<JSProxy> proxy,
            Handle<FixedArray> keys);
        bool IsShadowed(Handle<Object> key);
        bool HasShadowingKeys();
        Handle<OrderedHashSet> keys();

        Isolate* isolate_;
        // keys_ is either an Handle<OrderedHashSet> or in the case of own JSProxy
        // keys a Handle<FixedArray>. The OrderedHashSet is in-place converted to the
        // result list, a FixedArray containing all collected keys.
        Handle<FixedArray> keys_;
        Handle<JSReceiver> last_non_empty_prototype_;
        Handle<ObjectHashSet> shadowing_keys_;
        KeyCollectionMode mode_;
        PropertyFilter filter_;
        bool is_for_in_ = false;
        bool skip_indices_ = false;
        // For all the keys on the first receiver adding a shadowing key we can skip
        // the shadow check.
        bool skip_shadow_check_ = true;

        DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
    };

    // The FastKeyAccumulator handles the cases where there are no elements on the
    // prototype chain and forwords the complex/slow cases to the normal
    // KeyAccumulator. This significantly speeds up the cases where the OWN_ONLY
    // case where we do not have to walk the prototype chain.
    class FastKeyAccumulator {
    public:
        FastKeyAccumulator(Isolate* isolate, Handle<JSReceiver> receiver,
            KeyCollectionMode mode, PropertyFilter filter,
            bool is_for_in = false, bool skip_indices = false)
            : isolate_(isolate)
            , receiver_(receiver)
            , mode_(mode)
            , filter_(filter)
            , is_for_in_(is_for_in)
            , skip_indices_(skip_indices)
        {
            Prepare();
        }

        bool is_receiver_simple_enum() { return is_receiver_simple_enum_; }
        bool has_empty_prototype() { return has_empty_prototype_; }

        MaybeHandle<FixedArray> GetKeys(
            GetKeysConversion convert = GetKeysConversion::kKeepNumbers);

    private:
        void Prepare();
        MaybeHandle<FixedArray> GetKeysFast(GetKeysConversion convert);
        MaybeHandle<FixedArray> GetKeysSlow(GetKeysConversion convert);

        MaybeHandle<FixedArray> GetOwnKeysWithUninitializedEnumCache();

        Isolate* isolate_;
        Handle<JSReceiver> receiver_;
        Handle<JSReceiver> last_non_empty_prototype_;
        KeyCollectionMode mode_;
        PropertyFilter filter_;
        bool is_for_in_ = false;
        bool skip_indices_ = false;
        bool is_receiver_simple_enum_ = false;
        bool has_empty_prototype_ = false;

        DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
    };

} // namespace internal
} // namespace v8

#endif // V8_KEYS_H_
